| 摘要 |
<p>PROBLEM TO BE SOLVED: To prevent a bid form from being falsified or replaced by an electronic bidding system using the Internet. SOLUTION: At a bidding stage (a), companies A, B, and C as supply sides 1 generate bid forms respectively, ciphers them by using common keys 2a, 2b, and 2c that the companies have, and e-mails the ciphered bid forms 3a, 3b, and 3c to a purchase side 4. At a closing stage (b), the bid forms of the respective companies are merged into one, the hash value of the merged data is found, and a certificate 6 converted so that forgery can be detected is generated from the hash value and sent to the respective companies. At an open bid stage (c), the respective companies send their own common keys 2a, 2b, and 2c to the purchase side 4, which deciphers the ciphered bid forms 3a, 3b, and 3c by using the common keys and determines a successful bidder according to their contents.</p> |
